[PATCH v2 02/17] KVM: arm64: Reject the PVTIME vCPU attribute for protected VMs

[Fuad Tabba <fuad.tabba@linux.dev>]

pKVM currently doesn't support steal time for protected guests:
KVM_CAP_STEAL_TIME reports 0 for them. The host still accepts the
KVM_ARM_VCPU_PVTIME_CTRL attribute, whose IPA would point
kvm_update_stolen_time() at the guest's private memory on every vCPU
load. Return -EPERM for the attribute group instead.

Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/kvm/guest.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index b01d6622b8720..ab659795d4b2f 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -916,6 +916,10 @@ int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu,
 		ret = kvm_arm_timer_set_attr(vcpu, attr);
 		break;
 	case KVM_ARM_VCPU_PVTIME_CTRL:
+		/* Steal time is not advertised to protected guests. */
+		if (vcpu_is_protected(vcpu))
+			return -EPERM;
+
 		ret = kvm_arm_pvtime_set_attr(vcpu, attr);
 		break;
 	default:
@@ -939,6 +943,9 @@ int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu,
 		ret = kvm_arm_timer_get_attr(vcpu, attr);
 		break;
 	case KVM_ARM_VCPU_PVTIME_CTRL:
+		if (vcpu_is_protected(vcpu))
+			return -EPERM;
+
 		ret = kvm_arm_pvtime_get_attr(vcpu, attr);
 		break;
 	default:
@@ -962,6 +969,9 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
 		ret = kvm_arm_timer_has_attr(vcpu, attr);
 		break;
 	case KVM_ARM_VCPU_PVTIME_CTRL:
+		if (vcpu_is_protected(vcpu))
+			return -EPERM;
+
 		ret = kvm_arm_pvtime_has_attr(vcpu, attr);
 		break;
 	default:
-- 
2.39.5